Telephone system



J. C. FIELD. TELEPHONE SYSTEM. APPLICATION FILED raw/25.1917.

.UNITED STATES-,PATENT oEEICE.

JosEI'II C. EIELD, 0E. OENGENEW JERSEY, nssIGNoE To WESTERN ELECTRIC coMPANY; INCoEPoEATEn, or NEWIORK, N..Y., Av CoEPoEATIoN 0E NEW 'To a-ZZ 'uihom-z't may concern: n

. Be it knownthat L'JosEPH C. FIELD, a citizen of the United `States,residing at Orange,i' n the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exactdescription. i,

This invention relates to telephone sys-` tems in which telephone lines may be simultaneously employed for a variety of purposes, such as the transmisslon of both telegraphic and telephonie messages, and, for selective lsignalin telephone systems now in use it 1s the practice to phantom two metallic telephone lines extending' between .two widely separated points, for the transmission of telephonic messages therebetween, while employing each telephone line or a -portion thereof for the transmission of telephonie messages between points intermediate the terminals of the two lines. It is the object ofthe present invention to so equip two such lines, each of which mayor mayv not be s impleXed for the transmission of telephonie -messages betweenA terminals, and each of which may be employed for, selective signaling and for the transmission of telephonie messages between any two points thereon, that the telephone lines maybe phantomed Vbetween either terminal anda point intermediate the terminals, and

when so phanto'ined, to be used for the transmission of separate'telephonic messages between the' intermediate point. and both terminals, Aorbetween' terminals, without interferin -with the'use ofthe lines for selective signa ing, and local or through telephone and telegraph messages. This invention will be fully understood from a consideration of thev following descriptionltaken in connection with the accompanying drawing, showing vone .embodiment thereof. l

In the drawing there is shown a telephone line comprising line wires 5 and 6, which extends between two points a number of miles apart, for example, between Cincinnati and Columbus. Another telephone line, comprising line wires 7 and 8, extends between the samepointsl Each telephoneline is equipped with se-v lectors 10, 10, which may be of the type disclosed in the Craft et aZPatent No.1,140,120,

' Specification of Letters Patent. Patented D60- 16, 1919. Application mednay 25, 191'?. serial No'. 17o,s62.

and which may be selectively operated by spective lines from a battery l1, by the i11- termittent operation of a relay 12, controlled by an impulse transmitting key 13. Each line at the vimpulse sending end is equipped with retardation coils 14 and 15 and a condenser 16,

lmpulses of currenttransmitted over the re-4 for the purpose of graduatingthe current impulses, in order vthat they will not cause `any disagreeable thump in telephonieapparatus which may be `connected with vthe line wires during the'transmission of impulses. A telephone. set 17 ofthe usual construction may be located at thesendingend of each telephone line and at each station at lwhich a selector l0 is located.

For the purpose of the transmission of telegraphicl messages over each telephone line between terminal stations, each line may be simpleXed by means of retardation coils 20, one located at'each end, each coil,

being connected between the telephone line and a relay 21 controlled by a telegraph key 22 and controlling a telegraph'sounder (not shown). Each retardation coil 20 is noninductive to currents of telephonie frequency traversing the line 'wires 5 and 6,01 7 and 8 in parallel, but inductive to such luated to prevent interference with telephonic apparatus vwhich may be connected with the linevwires.

The apparatus hereinbefore described is that commonly employed inv systems in which a telephone line is used for the purpose of selective signaling, and the transmission of telephonie and telegraphic messages. v The apparatus shown to the left of .the dotted line l-lis located at one terminal station, the dotted line 4.-4 is located at the other terminal station. The apparatus shown bewhile that shown to the right of tween the dotted lines 2-2 and 3 3 is110 located at an intermediate station, tor convenience, designated as Xenia.

In order that the sect-ions of the two lines between Cincinnati and Xenia may be employed as a'phantom circuitffor the transphonic currents, is provided.

AIn phantoming the telephone lines, -retardation coils 30 non-inductive to currents of telephonie Jfrequency traversing the line wires 5 and 6 or T and 8, in parL llel but inductive to such currents traversing the line wires in series, have two windings connected with the line wires through condensers 3l, 3l which preventthe flow of direct current. Conductors 32 and 37, respectively, connect the windings of the retardation coils 30 and 20 with terminals of jacks 34, each adapted to be engaged by a plug 35 to which is connected a telephone set 36. A condenser 39, in each conductor 3T, prevents the passage of direct current.V A condenser 33 and a winding of a retardation coil 38 are legged from the conductors 32 and 37 to ground, in accordance with the well-known practice, to prevent the Morse thump from interfering with the phantom telephone circult.- Each winding of each retardation coil 38 is ot high impedance to currents of telephonie frequencyv to prevent the shunting thereof away from the telephone sets 36.

A Winding of a. retardation coil 40 which is of high impedance to currents of telephonie frequency is in circuit withtelegraph relay 2l to prevent the passage of telephonie currents. rEhe windings of the retardation coils 40 are however ot low impedance to telegraphic currents. A

ln order to isolate each telephone line into sections to prevent the passage of phantom currents between sections, retardation coils 41, 41, which are of low impedance to telephonie currents traversing the line wires of each telephone line in series, and to telegraphic currents traversing the line wires in parallel, but of high impedance to phantom telephonie or high Jfrequency currents traversing the linev wires in parallel, are included in series with the line wires. In order to preventsuch high-frequency currents as mayiilter through one retardation coil 41 from passing on to the othersection, a ref' tardation coil 42 of low impedance to highfrequency currents is connected in bridge of each telephone line between the retardation coils 4l, 41, and the middle points of the windings of these coils 42, 42, are connected together by agrounded conductor 43 which serves to practically short-circuit the two 4th'e simultaneous transmission of telephone and telegraphic messages, and current im pulses for selective signaling while at the same time the two telephone lines may be isolated into sections which are phantom and employed for the transmission of separate telephonie messages between the terminals andthe intermediate point at which the lines Y,

are divided into sections. clear from this description that the transmission ot these various messages is accomplished without any interference, so that the capacity of existing telephone lines may be increased, thereby avoiding the necessity of building new lines to care Jfor increase in business. Should it be desired at any time to employ the lines for the transmission of telephonie messages between terminal stations over a phantom circuit, this may be accomplished by connecting the two jacks 34, 34 at the intermediate station together by means of a looping cord (not shown). 'ln the same way, either terminal station could be connected with a station ori-"another telephone line which terminates at the`intermediate point.

W'hat is claimed is:

l. .A telephone system comprising twotelephone stations, a pair of conductively continuous line wires joining the stations, and mea-ns intermediate the stations for. electrically dividing the line wiresinto sections with respect to high-frequency currents traversing the line wires in parallel, the means electrically separating adjacent sections comprising two retardation coils of high impedance to such currents traversing the line wires in parallel connected in series therewith and a retardation coil of low impedance to such currents connected in bridge of the line wires between the irst mentioned coils. I

2. A telephone system comprising two stations, two telephone lines joining the stations, each comprising two conductively continuous line wires, signaling and telephonie apparatus in bridge of the line wires of each telephone line responsive to currents 'traversing the line wires in series, appara-- tus for phantoming the two telephone lines, Ytelephonie apparatus connected in bridge of the phantom circuit, and means intermediate the stations Jfor electrically dividing the line wires into sections with respect to telephonie It will also be currents traversing the phantom circuit, the V means electrically separating adjacent sections comprising two retardation .coils of high impedance to such currents connected in series withthe line wires of each telephone line anda retardation coil of low impedance to such currents connected in bridge of the line wires of eachV telephone line between the iirst-mentioned coils.

3. A telephone system comprising two stations, two telephone lines joining the, stations each comprising two conductively continuous line wires, telephonie apparatusin circuit with the line wiresl of each telephone l line responsive to currents traversing the line wires in series, apparatus for phantoming the two telephone lines, telephonie apparatus connected in the phantom circuit, and

wires of each telephone line and al conductor joining the middle points ofthe impedance coils.

4. A. telephone system comprising two stations, two telephone lines joining the stations each comprising two conductively continuous line wires, telephonie apparatus in circuit with the line wires of each telephone line responsive to currents traversing the line wires in series, apparatus for phantoming the two telephone lines, telephonie apparatus connected in the phantom circuit, and inea-ns intermediate the stations fpr electrically dividing the linev wires into s ections with respect to telephonie currents traversing the line wires in parallel, the means electri- V cally separating adjacent sections comprising two retardation coils of high impedance to such currents connected in series with the lifne wires of each telephone line, a retardation coil of low. impedance to such currents connected in bridge of the'line wires of each telephone line between the first-mentioned coils, and a grounded conductor joining the middle points ofthe coils of low impedance.

In witness Whereof'I hereunto subscribe my name this 28rd dayfof May, A. D. 1917.

4JosEPi-i o. rinnn. 

